SEATAC, Wash. (AP) -- A "suicidal" airline employee stole an empty Horizon Air turboprop plane, took off from Sea-Tac International Airport and was chased by military jets before crashing into a small island in the Puget Sound on Friday night, officials said.

Preliminary information suggests the crash occurred because the 29-year-old man was "doing stunts in air or lack of flying skills," the Pierce County Sheriff's Department said.

Ed Troyer, a spokesman for the sheriff's department, said on Twitter the man was suicidal and there was no connection to terrorism.

Video showed the Horizon Air Q400 doing large loops and other dangerous maneuvers as the sun set on the Puget Sound. There were no passengers aboard.

Authorities initially said the man was a mechanic but Alaska Airlines later said he was believed to be a ground service agent employed by Horizon. Those employees direct aircraft for takeoff and gate approach and de-ice planes.

Witnesses reported seeing the plane being chased by military aircraft before it crashed on Ketron Island, southwest of Tacoma, Washington. Troyer said F-15 aircraft scrambled out of Portland, Oregon, and were in the air "within a few minutes" and the pilots kept "people on the ground safe."

The sheriff's department said they were working to conduct a background investigation on the Pierce County resident, whose name was not immediately released.

The aircraft was stolen about 8 p.m. Alaska Airlines said it was in a "maintenance position" and not scheduled for a passenger flight. Horizon Air is part of Alaska Air Group and flies shorter routes throughout the U.S. West. The Q400 is a turboprop aircraft with 76 seats.

Pierce County Sheriff Paul Pastor said the man "did something foolish and may well have paid with his life."

The man could be heard on audio recordings telling air traffic controllers that he is "just a broken guy."

An air traffic controller called the man "Rich," and tried to convince him to land the airplane.

"There is a runway just off to your right side in about a mile," the controller says, referring to an airfield at Joint Base Lewis-McChord.

"Oh man. Those guys will rough me up if I try and land there," the man responded, later adding "This is probably jail time for life, huh?"

Later the man said: "I've got a lot of people that care about me. It's going to disappoint them to hear that I did this ... just a broken guy, got a few screws loose, I guess."

Flights out of Sea-Tac, the largest commercial airport in the Pacific Northwest, were temporarily grounded during the drama.

The U.S. Coast Guard sent a 45-foot vessel to the crash scene after witnesses reported seeing a large plume of smoke in the air, Petty Officer Ali Flockerzi said. Video showed fiery flames amidst trees on the island, which is sparsely populated and only accessible by ferry.

Alaska Airlines said no structures on the ground were damaged.

Royal King told The Seattle Times he was photographing a wedding when he saw the low-flying turboprop being chased by two F-15s. He said he didn't see the crash but saw smoke.

"It was unfathomable, it was something out of a movie," he told the newspaper. "The smoke lingered. You could still hear the F-15s, which were flying low."

"Our hearts are with the family of the individual aboard, along with all of our Alaska Air and Horizon Air employees," Horizon Air Chief Operating Officer Constance von Muehlen said in a video posted on Twitter.